Summary of Significant Accounting Policies (Balances Related to Joint Ventures (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 entities		Dec. 31, 2010		Dec. 31, 2009
VIE Table
Number of Unconsolidated Joint Ventures Considered Variable Interest Entities	3
Carrying Value of Investment in Unconsolidated Company	$ 33.5		$ 31.7
Maximum Loss Exposure From Investment In Unconsolidated VIEs	33.5		31.7
Carrying Value of Guarantee Obligations	(17.7)		(25.2)	[1]	(36.3)
Maximum Loss Exposure from Guarantee Obligations	$ (57.0)	[1]	$ (63.7)	[1]

[1] We are party to guarantees of the third-party debt of these joint ventures and our maximum loss exposure is equal to the maximum monetary obligation pursuant to the guarantee agreements. In 2009, we recorded a liability for our probable future obligation under a guarantee to the lender of one of these ventures. Pursuant to an agreement with the lender, we may make partner loans to this joint venture that will reduce our maximum guarantee obligation on a dollar-for-dollar basis. The carrying value of our recorded guarantee obligations is included in other liabilities in our Consolidated Balance Sheets.